Upper Respiratory Infections: How Long a Cold Should Last, When Sinusitis Needs Antibiotics and the Sore Throat Rule
Almost all of this needs no antibiotic. The useful knowledge is not which tablet to take — it is how long each of these is supposed to last, so you can tell an ordinary course from one that has gone wrong. Most unnecessary antibiotic courses are prescribed to people whose infection was behaving completely normally.
This page covers the nose, sinuses, throat and voice box. Chest infections and pneumonia are a different problem with different rules, covered in our guide to pneumonia and chest infections.
📅 How long a cold actually lasts
| When | What is normal |
|---|---|
| Days 1 to 2 | Sore or scratchy throat, sneezing, tiredness. Mild fever possible in the first day or two |
| Days 2 to 4 | The worst days. Blocked and running nose, headache, aching, cough beginning |
| Days 4 to 7 | Nasal discharge thickens and often turns yellow or green — which is normal and not a sign of bacteria. Congestion dominates |
| Days 7 to 10 | Most symptoms resolving. Congestion and cough still present |
| Weeks 2 to 3 | Cough alone can persist for two to three weeks and this is entirely expected. It is the airway lining recovering, not a lingering infection |
Adults get two to four colds a year, children considerably more. A run of colds through winter in a household with young children is not a sign of a weak immune system.
💡 The colour of mucus is the single most useful myth to drop. Yellow and green come from enzymes released by the white cells that arrive in any inflammation, viral included. They appear in a perfectly ordinary cold around day four and they say nothing about whether bacteria are present. Clear mucus equally does not rule infection out.
What matters is direction and duration, not colour.
👃 Sinusitis: the ten-day rule
Acute sinusitis follows almost every cold to some degree — facial pressure, blocked nose, reduced smell, a cough worse when lying down. Over nine in ten cases are viral, and the great majority resolve without antibiotics.
There are exactly three situations in which antibiotics are indicated, and all of them are about pattern rather than severity on any single day.
| Criterion | Detail |
|---|---|
| 1. Ten days without improvement | Symptoms persisting at the same level or worse for 10 days or more, with no sign of turning the corner |
| 2. Severe from the start | Fever of 39 degrees or above with purulent nasal discharge and facial pain, together, for three to four consecutive days |
| 3. Double worsening | Getting better for a few days, then clearly worse again with returning fever or increasing facial pain. The most reliable single indicator |
When one of those applies, the first-line choice matters:
- 🔹 Augmentin (Amoxicillin with Clavulanate) — 500/125 mg three times daily, or 875/125 mg twice daily, for 5 to 7 days in adults. The clavulanate covers the resistant organisms that plain amoxicillin misses in sinuses
- 🔹 Amoxil (Amoxicillin) alone remains reasonable in uncomplicated cases without risk factors
- 🔹 Vibramycin (Doxycycline) — 200 mg on day one then 100 mg daily — where there is penicillin allergy
- 🚫 Macrolides are no longer recommended for sinusitis, because resistance in the main organism is now too high in most regions for them to be reliable
Alongside, the measures that genuinely help: saline nasal irrigation, an intranasal steroid spray which reduces swelling around the sinus openings, paracetamol or an anti-inflammatory for pain, and a short course — three to five days at most — of a decongestant spray. Our allergy and nasal range carries the spray options.
🚨 Sinusitis red flags — same day, not next week. Swelling or redness around the eye, a bulging eye, double vision or reduced vision; severe headache with vomiting, neck stiffness or confusion; swelling of the forehead. The sinuses sit next to the eye and the brain, and infection can spread. These are rare and they are the reason sinusitis is not something to simply endure indefinitely.
🗣️ Sore throat: four questions decide everything
Most sore throats are viral and need nothing. The small group that benefits from antibiotics is identified by a score, and the score takes ten seconds.
One point each for:
- 🌡️ Fever — history of it during this illness
- 🚫 Absence of cough — a cough makes strep less likely, not more
- 🩸 Tender, swollen glands at the front of the neck
- 🟡 White patches or exudate on the tonsils
| Score | What it means |
|---|---|
| 0 to 1 | Strep unlikely. No test, no antibiotic. Symptomatic treatment |
| 2 | Consider a throat swab or rapid antigen test |
| 3 to 4 | Strep reasonably likely. Test, or treat where testing is not available |
And the number that puts this in perspective: antibiotics shorten a sore throat by about 16 hours on average. The reason for treating confirmed strep is not speed — it is preventing the rare complications, including rheumatic fever, and reducing spread.
Where treatment is indicated: penicillin V for 10 days, or amoxicillin 500 mg twice daily for 10 days. The full ten days matters here more than in most infections, and stopping at day five because the throat feels better is the usual error. Zithromax (Azithromycin) over five days is the alternative for genuine penicillin allergy — which is its proper place in this topic rather than as a first choice.
🚨 Sore throat emergencies. Severe pain on one side with difficulty opening the mouth, a muffled hot-potato voice, drooling because swallowing saliva hurts too much, or swelling pushing the tonsil across — that is a quinsy, an abscess, and it needs drainage the same day.
Also urgent: any difficulty breathing, noisy breathing, inability to swallow fluids, or a stiff neck with light sensitivity.
🎤 Laryngitis and the three-week rule
Viral laryngitis makes the voice hoarse or absent for a few days to two weeks. The treatment is simple and specific:
- 🤐 Rest the voice — and do not whisper. Whispering strains the vocal folds more than speaking softly does. Soft normal speech or silence, not whispering
- 💧 Hydration and humidity, which the vocal folds genuinely need
- 🚭 No smoking, and avoid throat clearing, which traumatises the folds repeatedly
- 🚫 Reflux is a common cause of recurrent hoarseness without any infection
⚠️ Hoarseness lasting more than three weeks needs the vocal cords looked at with a laryngoscope, particularly in anyone who smokes or drinks heavily. Persistent hoarseness is the commonest presenting symptom of laryngeal cancer, and it is highly treatable when found early. Three weeks is the threshold, not three months.
👂 The blocked ears nobody explains
Ears that feel full, muffled or crackly for weeks after a cold are eustachian tube dysfunction — the tube connecting the middle ear to the back of the nose has swollen shut, so pressure cannot equalise. It is harmless, it is miserable, and it can take four to six weeks to settle.
- 💨 Autoinflation — pinch the nose and swallow, or blow gently against a pinched nose. Several times a day, gently. There are small balloon devices designed for this with reasonable evidence behind them
- 👃 Treat the nose, since the problem is at the nasal end — saline rinses and a nasal steroid spray
- 🍬 Chewing gum or sucking a sweet, which works through the same mechanism
- ✈️ Avoid flying with a completely blocked nose if you can. If you must, use a decongestant spray 30 minutes before descent and swallow repeatedly on the way down
- 🚫 Nothing into the ear canal. Cotton buds, oils and drops do not reach the problem, which is behind the eardrum, and they cause their own injuries
- 📞 Seek review for hearing loss that is not improving after a few weeks, severe pain, discharge, or dizziness with hearing loss
💊 Symptomatic treatment, graded by whether it works
| Worth doing | Not worth it |
|---|---|
| Paracetamol or an anti-inflammatory for pain, fever and that awful aching. The best-evidenced thing on either list | Antibiotics for an ordinary cold or an early sore throat — no effect, and side effects in a meaningful minority |
| Saline nasal irrigation or spray — cheap, safe, modestly effective, and usable for as long as you like | Steam inhalation over a bowl — no proven benefit and a real scald risk, particularly with children in the house |
| Honey, in warm water or on its own, which outperforms placebo for cough in adults and in children over one year | Honey under one year of age — botulism risk. Never |
| Salt-water gargles for throat discomfort | Decongestant spray beyond 3 to 5 days — causes rebound congestion worse than the original, and people get stuck on it for years |
| Sleeping propped up, which reduces night-time cough and congestion | Vitamin C to prevent colds in the general population — it does not. Zinc and echinacea have inconsistent, weak evidence at best |
| Fluids and sleep, which are not filler advice —> fever and mouth breathing lose water fast | Stacking combination remedies — the commonest cause of accidental paracetamol overdose, because the same ingredient appears in three products |
One specific warning on that last point: check every cold and flu remedy for paracetamol content before adding a separate paracetamol tablet. Exceeding 4 g in 24 hours causes liver injury, and it is done accidentally every winter.
🚫 Why azithromycin should not be the default
It is the most commonly requested antibiotic for respiratory symptoms and one of the least appropriate for most of them.
- 📉 Resistance. Macrolide resistance in Streptococcus pneumoniae — the main organism in bacterial sinusitis — now exceeds a third in many regions, which is why guidelines moved away from it for this indication
- 🫀 Heart rhythm. It prolongs the QT interval, and regulators have issued specific warnings about cardiovascular death risk, particularly alongside other QT-prolonging drugs or with existing arrhythmia
- ⏳ Its long tissue half-life, which makes the short course convenient, also means low drug levels persist for weeks afterwards — conditions that actively select for resistant bacteria
It remains a genuinely useful drug: atypical pneumonia, penicillin allergy, certain sexually transmitted infections, and selected chronic lung disease. The range is in the antibiotics category, and the pneumonia indications are covered on our chest infection page.
🩺 Who should have a lower threshold
The watch-and-wait approach above assumes an otherwise healthy adult. These groups should seek advice earlier rather than ride it out:
- 👴 Over 65, and anyone frail
- 🫁 Asthma or COPD — a cold is the commonest trigger of an exacerbation, and the action plan should be used early. See our guide to chronic bronchitis
- 🍬 Diabetes, where infection destabilises glucose and glucose slows recovery
- 🫀 Heart failure or significant heart disease
- 🛡️ Immunosuppression — chemotherapy, transplant medication, high-dose steroids, biologics, absent spleen. A low threshold here is not caution, it is necessary
- 🤰 Pregnancy
- 👶 Infants, where fast breathing, ribs drawing in, poor feeding or unusual sleepiness are the signs that matter rather than temperature
💉 Prevention that does something
- 🧼 Hand washing, and keeping hands away from eyes and nose — the main route of transmission is hand to face rather than through the air
- 💉 Influenza vaccination annually, plus pneumococcal and COVID-19 vaccination where indicated by age or condition. This is the only intervention that reduces severity rather than just frequency
- 🚭 Not smoking, which roughly doubles the duration of respiratory infections
- 😴 Sleep, where short sleep measurably increases susceptibility in challenge studies
- 🧴 Humidity in very dry heated rooms, which keeps the nasal lining working
- 🏠 Staying home while feverish, which is the part that protects everyone else
📞 When to seek help
Emergency:
- Difficulty breathing, noisy breathing or unable to speak in full sentences
- Unable to swallow saliva, or drooling with severe throat pain
- Swelling or redness around the eye, a bulging eye, or visual change
- Stiff neck with light sensitivity, a rash that does not fade on pressure, or confusion
- Blue or grey lips, or fainting
- In a baby: fast breathing, ribs drawing in, poor feeding or unusual drowsiness
Same day or next day:
- Sinus symptoms 10 days or more without improvement, or clearly worse after improving
- Fever of 39 degrees with purulent discharge and facial pain for three to four days
- Severe one-sided throat pain, or a sore throat score of 3 or 4 with high fever
- Any respiratory infection in the higher-risk groups above
- Chest pain, breathlessness, or coughing blood — this has moved below the upper tract
- Unable to keep fluids down, or passing very little dark urine
Worth an appointment: hoarseness beyond three weeks; cough beyond three to four weeks; blocked ears or reduced hearing not improving after a few weeks; four or more episodes of sinusitis or tonsillitis in a year; or using a decongestant spray for longer than a week.
❓ Frequently asked questions
How long should a cold last?
Worst on days two to four, most symptoms resolving by day seven to ten, and the cough alone commonly persisting two to three weeks. That lingering cough is the airway lining recovering, not an infection that needs antibiotics.
Does green mucus mean I need antibiotics?
No. The colour comes from enzymes released by white cells in any inflammation, viral included, and typically appears around day four of an ordinary cold. Direction and duration matter; colour does not.
When does sinusitis need an antibiotic?
In three situations: ten days or more without improvement; fever of 39 degrees with purulent discharge and facial pain together for three to four days; or clear worsening after an initial improvement. Over nine in ten cases are viral.
What is the Augmentin dose for sinusitis?
500/125 mg three times daily, or 875/125 mg twice daily, for five to seven days in adults. Doxycycline is the alternative in penicillin allergy. Macrolides are no longer recommended for sinusitis because of resistance.
Do I need antibiotics for a sore throat?
Usually not. Score one point each for fever, absence of cough, tender neck glands and tonsillar exudate. Nought to one means no antibiotic. Three to four means testing or treatment. Antibiotics shorten a sore throat by about 16 hours.
Why does a cough make strep throat less likely?
Because streptococcal infection is confined to the throat, whereas a cough indicates the viruses that affect the whole respiratory lining. Absence of cough is one of the four scoring points for exactly that reason.
How long can hoarseness last before I should worry?
Three weeks. Beyond that the vocal cords need examining, particularly in anyone who smokes or drinks heavily, because persistent hoarseness is the commonest first symptom of laryngeal cancer and it is highly treatable when found early.
My ears have been blocked for weeks after a cold. What helps?
That is eustachian tube dysfunction and it can take four to six weeks. Gentle autoinflation several times a day, saline rinses and a nasal steroid, and chewing gum. Nothing should go into the ear canal, since the problem is behind the eardrum.
How long can I use a decongestant nasal spray?
Three to five days at most. Beyond that it causes rebound congestion worse than the original problem, and people remain stuck on it for years. Saline spray has no such limit.
Why is azithromycin not the right choice for most respiratory infections?
Resistance in the main sinusitis organism now exceeds a third in many regions, it prolongs the heart QT interval with a specific regulatory warning, and its long tissue half-life leaves low levels that select for resistant bacteria for weeks.
📑 Sources and editorial
- National and specialist society guidance on acute sinusitis, including the ten-day, severe-onset and double-worsening criteria for antibiotic therapy and first-line agent selection
- Guidance on acute sore throat, including the Centor and FeverPAIN scoring systems, testing strategies and duration of penicillin therapy
- Cochrane reviews of antibiotics for sore throat, for the common cold and for acute purulent rhinitis, including the magnitude of symptom reduction
- Natural history studies of the common cold and of post-infectious cough duration
- Prescribing information for amoxicillin-clavulanate, amoxicillin, doxycycline and azithromycin
- Surveillance data on macrolide resistance in Streptococcus pneumoniae, and regulatory safety communications on azithromycin and QT prolongation
- Cochrane reviews of saline nasal irrigation, intranasal corticosteroids in sinusitis, honey for acute cough, steam inhalation, and vitamin C, zinc and echinacea
- Guidance on rhinitis medicamentosa following prolonged topical decongestant use
- Guidance on persistent hoarseness and referral thresholds for laryngoscopy
- Evidence on autoinflation for eustachian tube dysfunction and otitis media with effusion
- Related reading: pneumonia and chest infections, pharyngitis and sore throat, chronic bronchitis
- Related products: Augmentin, Amoxil (Amoxicillin), Vibramycin (Doxycycline), Zithromax (Azithromycin), antibiotics category, allergy and nasal category
- RXshop Editorial Team — reviewed by Emily Chen, MD, MPH — Internal Medicine Specialist
Medical Disclaimer: The information in this article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek guidance from a qualified healthcare provider with any questions you may have regarding a medical condition, and before starting, stopping or changing any medication.